Q: my iphone 6s has completely had a melt down after ios 10

Hello Ronjoy,
Thank you for using Apple Support Communities. 

I understand from your post that after updating your iPhone 6s to iOS 10 your iPhone will not shut down properly. I know how important it is for your iPhone to work smoothly after updating the software. In a situation like this, I recommend force restarting your iPhone.

Restart your iPhone, iPad, or iPod touch

If this does not resolve the issue the next step would be to try restoring your iPhone while it is in recovery mode. The following articles will provide you with the steps to restart your iPhone and to restore it in recovery mode: 


If you can‘t update or restore your iPhone, iPad, or iPod touch​

Best Regards